Treating microporous material

ABSTRACT

Microporous elastomeric sheet material, suitable for use in making shoe uppers, is pigmented throughout its thickness by impregnating it with a dilute aqueous pigmented latex, to deposit pigment within the micropores. Preferably the latex is anionic and the impregnated sheet is treated with acid; this produces a pigmented sheet of superior uniformity.

United States Patent Civardi et a1.

[ Feb. 13, 1973 TREATING MICROPOROUS MATERIAL Inventors? Frank PeterCivardi, 98 Kiwanis Drive, Wayne, N.J.; Hans-George Kuenstler, 149-3212th Road, Whitestone, NY. 11357 Filed: Dec; 21, 1970 Appl. No.: 100,290

US. c1. ..117/77, 117/9s, 117/119, ll7/138.8 D, 117/163, ll7/DIG.9 1m.(:1. ..B44.d 1/02 Field of Search... 1 17/98, 98 F, 138.8 D, DIG. 9,

[56] A References Cited UNITED STATES PATENTS 2,995,512 8/1961 Weidneret a]. ..1 17/163 X 3 232,786 2/ I 966 Kellman 3,455,727 7/1969 Dye117/1388 D Primary Examiner-Edward G. Whitby- Attorney- -Abner Shefferand F. W. Wyrnan 57 ABSTRACT 18 Claims, No Drawings microporous sheetmaterial, particularly fleeceless elastomeric sheet material for use inthe manufacture of shoe uppers.

One type of microporous sheet material suitable for shoe uppers is anelastomeric sheet, preferably of elastomeric polyurethane, having a porevolume of over 40 percent, e.g., about 50-80 percent, typically about 60percent, and substantially free of preformed fibrous reinforcing fabric,This material may be given a surface finish, as by treating its uppersurface to produce thereon a thin relatively dense surface layer ofpigmented polymer. (Such microporous materials, the finishing thereofand the nature and amounts of materials employed are describedmore fullyin the copending application of Civardi and Kuenstler entitled SurfaceTreatment filed July 21, 1970 Ser. No. 56,936, whose entire disclosureis incorporated herein by reference.)

In accordance with one aspect of the present invention the microporoussheet material is pigmented throughout its thickness by impregnating itwith a dispersion of pigment in a liquid non-solvent for the sheetmaterial, depositing the pigment within the micropores thereof, andremoving said non-solvent.

In a preferred form of the invention the amount and type of pigment thatis so deposited within the sheet material is related tofthe pigmentconcentration in the final dense surface layer. Thus the concentrationof pigment deposited within the micropores is generally less than thepigment concentration in the dense surface layer, e.g., some -60percent, preferably about to 40 percent of the pigment concentration inthe dense surface layer. For example, if thematerial is to be treated toproduce thereon a thin dense fused but breathable (water vaporpermeable) surface layer whose black pigment concentration is, say about6 to ID percent (based on the weight of the dense surface layer), thesheet material (prior to formation of the surface layer) may be treatedto deposit, and bond, say about 2 to 3 percent (based on the weight ofthe sheet material) of similar black pigment within the micropores. Theresulting product, after the surfacefinishing operation, will have adark blacksurface and a gray body appearance, so that, at a cut edge ofthe sheet, there will be a marked contrast between the lighter cut edgeand the darker top surface. However by burnishing the cut edge so as tofuse and densify the polymeric material there, the contrast iseliminated or markedly reduced, the formerly light edge being darkened,by densification, giving it an appearance similar to that of the topsurface. In this way a smooth attractive, n'eat dense edge is obtainedwithout the need for conventional more complicated operations, whichinvolve skiving the material and folding itover so as to produce an edgeat which the only finished top surface is visible. For best matching, ofcourse, the colors of the pigments should be similar. For instance brownpigment should be deposited in the micropores when the surface layer isto be made brown. For colors other than black the pigment concentrationsin the dense surface layer are generally above 10 percent, e.g. 15, 20,30 or 40 percent and the amount of pigment deposited in the microporesis correspondingly higher.

The microporous sheet before treatment with the pigment, is preferablysubstantially free of coloring pigment. Because of its microporousstructure it looks white even though the polymer of which it is made issubstantially colorless; owing to yellowing or browning of the polymer,the microporous sheet may appear, say, cream-colored rather than purewhite. It will be understood that the unpigmented microporous sheetmaterial 'can be produced in large quantities and then, in accordancewith this invention, different large pieces (e.g. rolls several feet inlength) of the same sheet material can be pigmented with differentcolored pigments (e.g. one piece treated with black dispersion, anotherwith brown, still another with blue, etc.) appropriate to the color ofthe surface-finishing to be applied to the individual large piece.

In a particularly suitable process, the microporous sheet material isimpregnated with a pigmented latex which is a blend of a dispersedpigment with an aqueous emulsion of a polymer. The impregnated sheet issqueezed to express excess pigmented latex and then, with its internalsurfaces still wet with the latex, is subjected to a precipitant for thepolymer and pigment. In a preferred case, in which the polymer andpigment are dispersed in the aqueous medium with the aid of an nonionicsurfactant), the precipitant is suitably an acid,

preferably a dilute aqueous solution of an acid (e.g. 5

percent aqueous BC] or 10 percent aqueous acetic acid). It has beenfound that it is sufficient to immerse the sheet into a bath of theprecipitant. The material can then be rinsed, as in a water bath. Thisprocess yields products of improved color uniformity throughout thethickness and area of the sheet. In contrast, if the latex-impregnatedsheet is simply allowedto dry, without the treatment with a precipitanta much less evenly colored material is obtained, the concentration ofpigment being greater near the surfaces of the sheet than in theinterior,'and, when a blend of pigments. is used, the pigments'tend tobe uneven distributed, or partial separated, with respect to each other.

The pigmented latex should be one which has a small enough particle size(e.g. below 1 micron) to permit it to be forced into the interior of themicroporous material. Preferably the pigmented latex is dilute,containing well below 20 percent solids and preferably well below 10percent solids (e.g. about 1 to 6 percent) and is a stable latex whichdoes not tend to coagulate or precipitate when worked duringimpregnation witn nip rollers. These properties can be easily determinedby simple tests using water-diluted commercially available latices.Thus, it has been found for instance that excellent results areobtained, when the following latices are diluted and used in thisinvention: Rohrn 8L Haas Rhoplex AC-6l which is an anionic polyacrylatelatex containing 45-47 percent solids, having a pH of 9.5-l0.0, aminimum film of formation temperature of 20 C and a clear film ultimatehardness (Tukon [KI-lNl) of 1.2; Rohm &'I-Iaas Rhoplex MV-l which is ananionic polyacrylate latex containing 45.5-46.5 solids, having a pH of9,040.0, a minimum film formation temperature of 8 C and a clear filmultimate hardness (Tukon[KI-IN]) of less than 1; Tylac FA562C which isan anionic carboxylated styrene modified butadiene-acrylonitritecopolymer latex containing 38 percent solids, having a pH of 8.5-9.0,and a viscosity less than 70 cps. Preferably, the polymer is one whichforms a water-insoluble flexible film; advantageously it is anelastomer.

The pigmentzpolymer ratio in the latex may be varied. Preferably itfalls within the range of about 0.3:1 to 2:1 more preferably about 1:1.The concentration of polymer in the pigmented latex may be, for instancein the range of about 1 to 5 percent, and the concentration of pigmentin the pigmented latex may be, for instance, in the range of about 1 to5 percent.

The pigmented latex may be impregnated into the microporous sheetmaterial-in various ways. One convenient method is by vacuumimpregnation, e.g., by removing much of the air from the sheet materialby placing the material under subatmospheriq pressure (e.g. a pressurebelow 200mm Hg absolute, preferably below about 50 mm Hg absolute) in avessel and drawing the pigmented latex into the evacuated sheetmaterial. impregnation may also be effected by passing the sheetmaterial through a bath of the pigmented latex while alternatelysqueezing the sheet material to displace much of the air (as by means ofnip rolls) and allowing the material to reexpand while in the bath oflatex. The amount of pigmented latex is usually such as to deposit lessthan about percent, e.g. about I to 6 percent, total solids (based onthe weight of the dry sheet). For shoe upper materials it is mostpreferred that the amount deposited be less than that which materiallyaffects the flexibility of the sheet material. The amount deposited maybe regulated by controlling the concentrations of polymer and pigment inthe pigmented latex and by controlling (by suitable adjust ment of thesqueeze rolls used for that purpose) the amount of excess pigmentedlatex expressed from the impregnated sheet prior to the precipitationstep. Thus with a pigmented latex containing about 3 percent pigment and3 percent polymer good results have been obtained by controlling thesqueeze rolls so that the sheet retains about 80 to 100 percent, basedon the original dry weight of the sheet, of pigmented latex. Generallythe pore size of the sheet material is such that little if anyimpregnation into the sheet is attained on simply immersing it in a bathof the latex.

As indicated above, when the pigmented latex contains an anionicsurfactant, precipitation can be readily effected with aqueous acid.Other precipitating agents to which the sheet polymer is inert willsuggest themselves to those skilled in the art, e.g. solutions ofelectrolytes, e.g. NaCl or Na,SO of sufficiently high concentration,acid vapors (e.g. HCl), or solutions of salts whose cations (e.g. Ca)react with the anionic surfactant to give water-insoluble precipitates.

After the precipitation step, the sheet is preferably rinsed to removeprecipitant (e.g. rinsed in water and squeezed thoroughly) and may thenbe treated to apply a fused pigmented surface layer thereto. Water is apreferred rinsing agent; other liquids, which do not dissolve thepolymer making up the sheet or the deposited polymer, may be employed.In one especially suitable procedure, a surface of the rinsed wet sheetis treated with a pigmented solution of a polymer, (preferably athermoplastic elastomeric polyurethane containing pig ment dispersedtherein) in a solvent which attacks the sheet material and is alsomiscible with the water (or other rinse liquid), whereby the liquid inthe sheet acts to coagulate the applied pigmented solution in anadherent layer at said surface. A fused layer may be subsequently formedon this coagulated layer and the surface may be embossed or compressedto provide various grains or patent leather effects. Full details of theprocess for applying this coagulated layer and of the subsequentformation of a fused layer thereon, as well as a description of thenature of the products so produced is given in the application ofCivardi and Kuenstler previously mentioned, whose entire disclosures areincorporated herein by reference. Alternatively the sheet, after theprecipitation step, may be dried and its surface treated directly with asolvent for the sheet polymer to form a fused layer thereon; preferablythe solvent is applied here in the form of a solution containing athermoplastic elastomeric polyurethane having a pigment dispersedtherein, the procedure being the same as, or similar to, that used (inthe previously mentioned Civardi and Kuenstler application) for theformation of the fused layer over an intervening coagulated layer.

The following Example is given to illustrate this invention further. Inthis application all proportions are by weight unless otherwiseindicated.

EXAMPLE In this Example the sheet material is an unpigmented microporousthermoplastic elastomeric polyurethane sheet about 1.7 mm thick andweighing about 800 grams per square meter. The sheet is composed of twointegral layers of different densities, the upper layer (whose densityis about 0.4g/mm) being thinner and less dense than the strength-givinglower layer.

The sheet is placed in a chamber which is evacuated until the pressuretherein is below 50mm Hg absolute. A diluted pigmented latex containing3 percent pigment and 3 percent polymer solids, and containing ananionic dispersing agent, is allowed to enter the chamber so that itimpregnates the sheet. The sheet is then squeezed between nip rolls,outside the chamber, to express excess pigmented latex; at this stagethe sheet carries about -100 percent (based on the dry weight of thesheet) of the pigmented latex; it is a light brown (tan) color, somewhatlighter than the color of the latex, but it does not carry a visible (tothe naked eye) layer of pigmented latex on its outer surfaces.

The sheet is then directly immersed in a bath of 5 percent aqueoushydrochloric acid (at atmospheric pressure) for one minute, withoutsqueezing, and then rinsed or dipped in tap water, and squeezed toexpress excess water. After drying in a hot airoven, the sheet is foundto have gained about 3-5 percent in weight owing to the treatment.During the acid treatment, rinsing and subsequent squeezing, there ispractically no visual evidence of pigment loss from the sheet. (Incontrast, if the latex-impregnated sheet is not given the acid treatmentbut is directly rinsed and squeezed a great deal of color is expressed).ltseems that the acid penetrates very rapidly into the latex-impregnatedsheet (presumably by ion transport) even though the acid is aprecipitant for the anionic surfactant of the latex and even though nosqueezing or other physical treatment to aid in penetration is employed,despite the fact that the sheet is ordinarily not readily penetrated byacid; in contrast when the same dry untreated sheet,

used as the starting material, is immersed in the acid and then blotteddry it retains less than 20 percent, based on its own weight, of thedilute acid and much of this is in small pockets on the rough bottomsurface.

The physical characteristics, other than color, of the sheet (e.g.water-vapor transmission, flex life and strength) appear to beessentially unchanged by the treatment. Examination of the treated sheetwith the scanning electron microscope indicate no significant changesand no discernible microscopic masses of coagulated latex When thetreated material is given a brown finish as described in the previouslymentioned Civardi and Kuenstler application its surface color isconsiderably darker than the color of the underlying sheet and, inshoemaking process, a cut edge (such as is formed in cutting out theparts that are to form a shoe upper) shows a lighter color than thefinish. Burnishing the edge, however, (as by contact with a heated metalsurface to melt the polyurethane) darkens the edge considerably so thatthere is little or no contrast, in color, between edge and top surface,in the finished shoe. For example the edges of the quarters and vamp ofthe stitchdown shoe shown on pages 230 and 231 of Modern FootwearMaterials & Processes by W.E. Cohn (Fairchild Publications, 1969), andparticularly those edges which are to be exposed in the finished shoe(e.g. the rearwardly exposed edges of the vamp, say at the tongue, andthe forwardly facing edges of the quarters, say at the eyelet row) areburnished before the pieces are stitched together to form the upper. Theburnishing can be effected, for instance by bringing the cut edge intocontact with a hot roller which is at a temperature of say about 300 C,which is'well above the melting point of the polyurethane, so as to forma thin continuous fused layer (say about 0.01 to 0.05 mm thick) at theedge while the thickness of the material is substantially unchanged.

in the foregoing Example the pigmented latex is prepared by mixing theanionic latex known as Tylac FA 562C (carboxylated styrene-modifiedbutadieneacrylonitire copolymer latex, which has a total solids contentof 38 percent, a pH of 8.5-9.0, and a viscosity of less than 70 cps)with an aqueous dispersion of mixture of yellow, red and black pigments,(e.g. in a ratio of 40 yellow, 8 red, 1.5 black). This blend is thendiluted with sufficient water to reduce its solids content to 6 percent.

The particle diameters of the pigment particles and polymer particles ofthe pigmented latex generally fall within the range of about 0.1 to 1micron.

Similar results are obtained by substituting Rohm & Haas Rhoplex AC-61or Rhoplex MV-l for the Tylac latex.

The surfactants present in the dispersions used in this invention may beof the conventional type. Thus, typical anionic surfactants have ahydrophilic salt group (at one end of the molecule) attached to ahydrophobic (e.g. hydrocarbon) chain. The hydrophilic group may be, forinstance, a sulfoxy-containing group such as a sulfate or sulfonate, asin tetrasodium N-(1,2-dicarboxy ethyl)-N-octadecylsulfosuccinatev(Aerosol 22), dioctyl ester of sodium sulfosuccinic acid (Aerosol OT),lauryl alcohol sulfate (Duponol MB), or other higher alkyl sulfate suchas 7-ethyl-2-methyl4-undecanol sodium sulfate (Tergitol 4), sulfonatedcastor oil, alkyl aryl sodium sulfonate (e.g. dodecyl or tridecylbenzene sodium sulfonate, such as Santomerse No. 3), alkyl arylpolyether sodium sulfonate (Triton X-200). As mentioned non-ionicsurfactants may also be used. These generally have a long hydrophobicchain attached to a water-soluble.polyethylene oxide group; examples arepolyoxyethylated fatty alcohols (such as Emulphor ON 870) orpolyoxyethylated alkyl (e.g. nonyl) phenols (such as Tergitol NP-4orlgepal CO-630, CO-890 or CO-970).

The latices used in the practice of this invention are usually made byemulsion polymerization. For instance, an acrylate emulsion may be madeby polymerizing 40 parts of an acrylate ester (e.g. ethyl acrylate ormethyl acrylate) in 55 parts of water in the presence of 3.9 parts ofTriton X-200 (containing 28 percent of the surfactant active ingredient)and 1.1 parts of a 30 percent solution of hydrogen peroxide, at refluxtemperature at atmospheric pressure, the monomer being added gradually,with stirring, during polymerization in a manner well known to the art;after polymerization is substantially complete the latex is cooled toroom temperature and its pH is adjusted to, say, 9.0 by adding aqueous28 percent ammonium hydroxide. As indicated, the polymer in the latexmay be a copolymer having carboxyl groups (usually carboxylate saltgroups). These latices are well known in the art, as shown, forinstance, by the carboxylated latices (made with about 1 to 20 percentof carboxylcontaining monomer) described in such patents as Booth No.3,366,588, Altobelli et al No. 3,223,663, Sutton No. 2,767,153, McDowellNo. 3,037,881, Hurwitz No. 2,954,358 and McLaughlin et al No. 2,790,736;the general and specific disclosures of these patents with respect tothe latices of carboxyl-containing copolymers and with respect to thepigment dispersions that may be mixed therewith are incorporated hereinby reference.

While the invention finds its greatest utility for the treatment offleeceless elastomeric sheet material it may also be used with thosemicroporous materials in which there is a layer of microporouselastomeric material on a fibrous substrate (which substrate ispreferably impregnated with elastomeric material.) The microporous layeron the substrate may be, for instance, over 0.1 mm in thickness (e.g.about 0.2, 0.3, or even 1 or 2 mm in thickness and its pores mayconstitute some 25-80 percent (e.g. about 50 or percent) of the totalvolume of the microporous layer. Because of the small size of themicropores (below microns and preferably well below 50 microns) themicroporous layer absorbs only little, if any, water on simple immersion(without squeezing) in water free of surfactant; the volume of water soabsorbed is well below 50 percent of the pore volume of the microporouslayer. The substrate may be (as in several well known commerciallyavailable water-vapor prermeable leather substitute materials used forshoe uppers) a polyurethane-impregnated non-woven felted batt of fibersof polyester (e.g. polyethylene terephthalate). The burnishing may beeffected so as to spread a thin layer of fused polyurethane to coverexposed cut fibers at the cut edge of the piece being burnished.

Black pigmented Brown pigmented before after before after meltingmelting melting melting L 34 12 72.05 52.0 a +.75 +.l +9.7 +l3.5 b +3.05+.60 +l 5.0 +215 A L -22 -20.6 A a .65 3.8 A b 2.45 8.5 E 22.2 22.7

It will be seen that AL and E are well above 15 while A a and Ab arewell below that value.

It is understood that the foregoing detailed description is given merelyby way of illustration and that variations may be made therein withoutdeparting from the spirit of the invention. The Abstract given above ismerely for the convenience of technical searchers and is not to be givenany weight with respect to the scope of the invention.

We claim:

1. Process for the treatment of microporous fusible elastomeric sheetmaterial, said sheet material having a microporous elastomeric zonewhose thickness is 0.1 mm to 2 mm and in which pores constitute 25 to 80percent of the total volume of said zone, the size of the micropores ofsaid zone being such that the volume of water absorbed by said zone onsimple immersion in water is less than 50 percent of the pore volume ofsaid zone, which process comprises impregnating said material with adispersion of pigment in a liquid nonsolvent for the sheet material todeposit the pigment within the micropores of said zone, and removingsaid non-solvent while retaining the microporosity of said zone andsheet material.

2. Process for the treatment of microporous fusible elastomeric sheetmaterial which comprises impregnating said material with a dispersion ofpigment in a liquid non-solvent for the sheet material to deposit thepigment within the micropores of said sheet material, removing saidnon-solvent while retaining the microporosity of said sheet material,and including the step of forming on a surface of sheet material, aftersaid impregnation, a thin dense breathable pigmented surface layer whosecolor is like that of said deposited pigment whereby when a cut edge ofsaid sheet material is heated to form a thin fused layer of saidelastomeric material at said edge the color of said edge is similar tothe color of said upper surface.

3. Process as in claim 1 in which said non-solvent is water containingan anionic surface active dispersing agent, and said sheet material istreated, after said impregnation, and before removal of the water, witha precipitating agent which reduces the surface activity of saiddispersing agent whereby to form a wet pigmented sheet material whosepigment is fixed in nonmigrating form within said micropores.

4. Process as in claim 3 in which said dispersion includes a latex of ahigh polymer.

5. Process as in claim 4 in which said precipitating agent is an acidand is used in amount such that rinsing and squeezing of theacid-treated sheet results in the expressing of substantially no colorfrom the sheet.

6. Process as in claim 5 in which said dispersion includes a latex of anelastomer, contains less than 20 percent solids, and has apigmentzpolymer ratio which is in the range of about 0.3:1 to 2:1.

7. Process as in claims 3 in which said dispersion includes a latex ofan elastomer, contains less than 20 percent solids, and has apigmentzpolymer ratio which is in the range of about 0.3:l to 2:1 andthe impregnation is effected by placing the sheet material under asubatmospheric pressure below 200 mm Hg absolute and drawing thepigmented latex into the evacuated sheet material.

8. Process for the treatment of microporous fusible water-insolubleelastomeric sheet material which comprises impregnating said materialwith a dispersion of pigment in a latex of elastomeric high polymer todeposit the pigment within the micropores of said sheet material, andremoving the water of said latex while retaining the microporosity ofsaid sheet material, said dispersion having a solids content of lessthan 20 percent and a pigmentzpolymer ratio which is in the range ofabout 0.321 to 2:1 and containing an anionic surface active dispersingagent, said sheet material being treated, after said impregnation, andbefore removal of the water, with an acid precipitating agent whichreduces the surface activity of said dispersing agent whereby to form awet pigmented sheet material whose pigment is fixed in non-migratingform within said micropores, the amount said acid being such thatrinsing and squeezing of the acid-treated sheet results in theexpressing of substantially no color from the sheet, said process beingone in which said sheet material is a microporous polyurethanesubstantially free of fibrous reinforcement, said precipitating agent isan aqueous solution of acid to which said sheet material is inert, theconcentration of polymer in said dispersion being in the range of about1 to 5 percent, the concentration of pigment in said dispersion being inthe range of about 1 to 5 percent, whereby to deposit an amount ofsolids in said sheet material which does not materially affect theflexibility of said sheet material and is in the range of about 1 to 6percent total solids based on the weight of said sheet material, the wetsheet material is surface-treated after said precipitation with apigmented solution of a polymer in a solvent which attacks said sheetmaterial but is also miscible with the water in said sheet materialwhereby the water acts to coagulate the applied pigmented solution in anadherent layer at a surface of said sheet material.

9. Process as in claim 8 in which said pigmented solution containspolyurethane whereby to form an adherent coagulated pigmentedpolyurethane layer on said polyurethane sheet material and in which afused pigmented polyurethane layer is thereafter formed on saidcoagulated layer, the color of the pigment of said fused layer beinglike that of said deposited pigment but said fused layer beingdistinctly darker than the body of the pigmented sheet material, thepigment content of the latter being such that when a cut edge thereof isheated to form a thin fused layer of polyurethane material at said edgethe color of said edge is similar to the color of said upper surface.

10. Process as in claim 8 and including the step of rinsing said sheetmaterial with water after said precipitation and prior to said surfacetreating.

11. Process as in claim 1 in which the total weight of material sodeposited within said micropores of said zone less than about 10 percentof the weight of said microporous zone.

12. Process as in claim 11 in which said microporous zone has a porevolume of up to about 60 percent and said impregnation is such as todeposit said pigment within said micropores throughout the thickness ofthe microporous material.

13. Process as in claim 11 in which the impregnation is such that the vmicroporous material is colored without forming on its outer surface avisible layer of pigmented dispersion.

14. Process as in claim 11 in which air is removed from said microporesto facilitate the penetration of said dispersion therein.

15. Process as in claim 14 in which the removal of air is effected byplacing the sheet material under subatmospheric pressure.

16. Process as in claim 14 in which the removal of air is effected bysqueezing the sheet material.

' 17. Process as in claim 14 and including the step of squeezing out aportion of the dispersion from the microporous material before removingthe non-solvent.

18. Process as in claim 1 and including the step of forming a thin densebreathable pigmented surface layer on a surface of said microporous zoneafter said impregnation.

III i

1. Process for the treatment of microporous fusible elastomeric sheetmaterial, said sheet material having a microporous elastomeric zonewhose thickness is 0.1 mm to 2 mm and in which pores constitute 25 to 80percent of the total volume of said zone, the size of the micropores ofsaid zone being such that the volume of water absorBed by said zone onsimple immersion in water is less than 50 percent of the pore volume ofsaid zone, which process comprises impregnating said material with adispersion of pigment in a liquid non-solvent for the sheet material todeposit the pigment within the micropores of said zone, and removingsaid non-solvent while retaining the microporosity of said zone andsheet material.
 2. Process for the treatment of microporous fusibleelastomeric sheet material which comprises impregnating said materialwith a dispersion of pigment in a liquid non-solvent for the sheetmaterial to deposit the pigment within the micropores of said sheetmaterial, removing said non-solvent while retaining the microporosity ofsaid sheet material, and including the step of forming on a surface ofsheet material, after said impregnation, a thin dense breathablepigmented surface layer whose color is like that of said depositedpigment whereby when a cut edge of said sheet material is heated to forma thin fused layer of said elastomeric material at said edge the colorof said edge is similar to the color of said upper surface.
 3. Processas in claim 1 in which said non-solvent is water containing an anionicsurface active dispersing agent, and said sheet material is treated,after said impregnation, and before removal of the water, with aprecipitating agent which reduces the surface activity of saiddispersing agent whereby to form a wet pigmented sheet material whosepigment is fixed in non-migrating form within said micropores. 4.Process as in claim 3 in which said dispersion includes a latex of ahigh polymer.
 5. Process as in claim 4 in which said precipitating agentis an acid and is used in amount such that rinsing and squeezing of theacid-treated sheet results in the expressing of substantially no colorfrom the sheet.
 6. Process as in claim 5 in which said dispersionincludes a latex of an elastomer, contains less than 20 percent solids,and has a pigment:polymer ratio which is in the range of about 0.3:1 to2:1.
 7. Process as in claims 3 in which said dispersion includes a latexof an elastomer, contains less than 20 percent solids, and has apigment:polymer ratio which is in the range of about 0.3:1 to 2:1 andthe impregnation is effected by placing the sheet material under asubatmospheric pressure below 200 mm Hg absolute and drawing thepigmented latex into the evacuated sheet material.
 8. Process for thetreatment of microporous fusible water-insoluble elastomeric sheetmaterial which comprises impregnating said material with a dispersion ofpigment in a latex of elastomeric high polymer to deposit the pigmentwithin the micropores of said sheet material, and removing the water ofsaid latex while retaining the microporosity of said sheet material,said dispersion having a solids content of less than 20 percent and apigment:polymer ratio which is in the range of about 0.3:1 to 2:1 andcontaining an anionic surface active dispersing agent, said sheetmaterial being treated, after said impregnation, and before removal ofthe water, with an acid precipitating agent which reduces the surfaceactivity of said dispersing agent whereby to form a wet pigmented sheetmaterial whose pigment is fixed in non-migrating form within saidmicropores, the amount said acid being such that rinsing and squeezingof the acid-treated sheet results in the expressing of substantially nocolor from the sheet, said process being one in which said sheetmaterial is a microporous polyurethane substantially free of fibrousreinforcement, said precipitating agent is an aqueous solution of acidto which said sheet material is inert, the concentration of polymer insaid dispersion being in the range of about 1 to 5 percent, theconcentration of pigment in said dispersion being in the range of about1 to 5 percent, whereby to deposit an amount of solids in said sheetmaterial which does not materially affect the flexIbility of said sheetmaterial and is in the range of about 1 to 6 percent total solids basedon the weight of said sheet material, the wet sheet material issurface-treated after said precipitation with a pigmented solution of apolymer in a solvent which attacks said sheet material but is alsomiscible with the water in said sheet material whereby the water acts tocoagulate the applied pigmented solution in an adherent layer at asurface of said sheet material.
 9. Process as in claim 8 in which saidpigmented solution contains polyurethane whereby to form an adherentcoagulated pigmented polyurethane layer on said polyurethane sheetmaterial and in which a fused pigmented polyurethane layer is thereafterformed on said coagulated layer, the color of the pigment of said fusedlayer being like that of said deposited pigment but said fused layerbeing distinctly darker than the body of the pigmented sheet material,the pigment content of the latter being such that when a cut edgethereof is heated to form a thin fused layer of polyurethane material atsaid edge the color of said edge is similar to the color of said uppersurface.
 10. Process as in claim 8 and including the step of rinsingsaid sheet material with water after said precipitation and prior tosaid surface treating.
 11. Process as in claim 1 in which the totalweight of material so deposited within said micropores of said zone lessthan about 10 percent of the weight of said microporous zone. 12.Process as in claim 11 in which said microporous zone has a pore volumeof up to about 60 percent and said impregnation is such as to depositsaid pigment within said micropores throughout the thickness of themicroporous material.
 13. Process as in claim 11 in which theimpregnation is such that the microporous material is colored withoutforming on its outer surface a visible layer of pigmented dispersion.14. Process as in claim 11 in which air is removed from said microporesto facilitate the penetration of said dispersion therein.
 15. Process asin claim 14 in which the removal of air is effected by placing the sheetmaterial under subatmospheric pressure.
 16. Process as in claim 14 inwhich the removal of air is effected by squeezing the sheet material.17. Process as in claim 14 and including the step of squeezing out aportion of the dispersion from the microporous material before removingthe non-solvent.